TextGeo-SLAM: A LiDAR SLAM With Text Semantics and Geometric-Constraint-Based Loop Closure

A robust back-end module with loop closure detection is crucial for accurate positioning and mapping in LiDAR-based simultaneous localization and mapping (SLAM) systems, particularly in Internet of Things (IoT) environments where multiple devices collaborate. Traditional methods that rely on images or point clouds often fail in environments with similar structures or textures, leading to incorrect loop closures. To address this, we propose a novel LiDAR SLAM system that integrates a front-end odometry module, a loop closure detection module using text semantics and geometric constraints, and a global optimization module. By using cameras on an unmanned ground vehicle (UGV), the system captures text information from the environment, enabling semantic matching to identify potential loops. Geometric constraints help eliminate erroneous loops caused by identical text in different locations. Evaluations on datasets with similarly structured environments, such as indoor parking lots, outdoor campus areas, and mixed indoor–outdoor scenes, show that our method significantly improves loop closure detection accuracy and global precision compared to existing state-of-the-art approaches. Our research can support autonomous IoT systems and multiagent systems that rely on accurate positioning and mapping, with potential applications in embodied intelligence, self-driving cars, and smart cities.